A power driven ski-bob which is propelled by a power driven ski is a newcomer to the field of winter recreation.
Presently there is a polarization between outdoor winter sports enthusiasts. The purist adhere to skis propelled by gravity or skier's muscles, while the modernists enjoy mounting a snowmobile which employs brute force to propell itself and its riders. Power driven skis (shown in U.S. Pat. Nos. 3,853,192 and 3,966,010 which are herein incorporated by reference), and the present invention bridge this gap between the purists and the modernists. They do so by combining the excitement of using one's sense of balance to control and steer with the excitement of controlling one's propelling power, and they remove or reduce the objectionable aspects of snowmobiling. For example, the total weight of a current power driven ski-bob is around 30 pounds and it is propelled by a 31/2 HP engine, versus several hundred pounds that the average snowmobile weighs, which are pushed by approximately a 10 times larger engine. In contrast to snowmobiles, ski-bobs have a minimal effect on the trail they pass, they do not develop large kinetic energy that may endanger their rider and others and they are not likely to get stuck in the snow, since the average rider can lift the unit in one hand. The small engine generates less acustical energy which can be readily muffled to non-obtrusive levels. Further, power driven ski-bobs are characterized by their long and narrow footprints, and have no stability of their own. Thus, the rider has, like on a bicycle, to continuously generate centrifugal balancing forces, which makes riding a power driven ski-bob an involving and exciting experience. As will be explained later on, this characteristic of power driven ski-bob is closely related to the present invention.